Geochronologic and petrologic evolution of the magmatic suite associated with the Eocene Coroccohuayco deposit, and its role in the genesis of the associated Cu(-Au) porphyry-skarn mineralization, Tintaya District, Peru

Abstract

This thesis provide a detailed geochronologic and petrologic study of the magmatic suite associated with the Eocene Coroccohuayco porphyry-related Cu deposit, Peru, that presents an evolution from normal to high Sr/Y through time, and investigate the significance of magmatic processes in the genesis of the mineralization. The first two chapters present high-resolution geochronologic data of magmatic and hydrothermal events. They highlight that the mineralization event was very rapid (<100 ka) and occurred after ~5 Ma of sustained intracrutal magmatism and proto-pluton cannibalism. The third and fourth chapters present new petrographic, geochemical and isotopic data of whole rocks and minerals. They suggest that the chemistry of magmatic rocks was mostly acquired in the deep crust, and was further modified in the upper crust. We provide evidence that the magma from which the porphyries crystallized was more oxidized, more hydrous and S-richer than the precursor magmas. We were also able to monitor the behavior of volatiles and Cu during fluid exsolution.